This invention relates to single frequency microchip lasers.
In this specification, numbers in brackets refer to the references listed at the end of the specification, the teachings of which are incorporated herein by reference. The realization of practical single-frequency, diode-pumped, solid-state lasers has been the goal of several researchers over the past 20 years [1]. One approach has been the solid-state, unidirectional, nonplanar, ring oscillator [2]. While this approach provides the desired laser characteristics, it suffers from a complicated fabrication process and optical alignment is critical. A simpler approach is the miniature, linear, solid-state cavity [3-5]. Although there has been some work on multimode miniature flat-flat cavities [6], the most common design for single-mode miniature cavities uses one curved mirror to stabilize the resonator [3-5]. In U.S. Pat. No. 4,860,304, filed Feb. 2, 1988, there is disclosed a solid-state, optically pumped microchip laser in which the cavity length is selected so that the gain bandwidth of the gain medium is less than the frequency separation of the cavity modes. This relationship guarantees that only a single longitudinal mode will oscillate when the frequency of this mode falls within the laser gain region.